塔里木盆地2004年春季沙尘暴特征分析

利用逐日的Davis自动气象站和FD12水平能见度仪资料,分析了塔里木盆地2004年春季系统性沙尘暴和局地性沙尘暴的环流形势、气象要素及能见度变化特征.结果表明:(1)前期气温持续上升和特殊的地理环境以及下垫面条件为沙尘暴爆发提供了条件;(2)低压槽前暖平流提供了热力条件,低压槽前正涡度平流提供了动力条件;(3)下层锋区的加强是形成沙尘暴的动力因子,不稳定的大气层结是重要的局地热力因子,也是形成沙尘暴天气的内在动力;(4)系统性沙尘暴能见度变化趋势复杂;局地性沙尘暴能见度变化走向分明,器测值约为目测值2倍;(5)系统性沙尘暴持续时间长、强度大、各气象要素变幅很大;局地性沙尘暴持续时间短,各气象要素在短时间内有剧烈变化.

Analysis on the Features of Sandstorms in the Tarim Basin in Spring 2004

The Tarim Basin in Xinjiang is located in the middle-latitude westerly zone,the vapour from the Atlantic is caught by the Iranian Plateau and the Pamirs,so the precipitation occurs infrequently and the vegetation coverage is low in the basin.Moreover,atmosphere over the Tarim Basin is generally controlled by hot low and is unstable,and there is abundant sand and dust in the Taklimakan Desert.All these provide the conditions of occurring sandstorms.In this paper,the circumfluence situation,meteorological factors and visibility change features of systematic and local sandstorms in spring(from April to May) 2004 are analyzed by using the day-by-day data collected at the Davis automatic observation station and of FD12 horizontal visibility.The results are as follows:(1) Prophase continuous temperature increase,peculiar geographic environment and underlaying surface conditions provide the preconditions of occurring sandstorms;(2) Trough of warm advection offers heating power and the positive vortex advection offers dynamic power of occurring sandstorms;(3) Enhancement of lower-air front is a driving factor of forming sandstorms,and the unstable atmosphere is an important local heating power factor and also an inherent motive force of forming sandstorms;(4) The visibility variation trend during systematic sandstorms is complicated.The visibility variation trend during local sandstorms is clear,and the apparatus-observed value is double of the range estimation;(5) Systemic sandstorms are characterized by long duration,powerful intensity and high variation ranges of meteorological factors.However,local sandstorms are characterized by short duration and violent variation ranges of meteorological factors within short time.